148 lines
3.1 KiB
JavaScript
148 lines
3.1 KiB
JavaScript
/*!
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* Connect - compress
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* Copyright(c) 2010 Sencha Inc.
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* Copyright(c) 2011 TJ Holowaychuk
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* MIT Licensed
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*/
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/**
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* Module dependencies.
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*/
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var zlib = require('zlib');
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/**
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* Supported content-encoding methods.
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*/
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exports.methods = {
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gzip: zlib.createGzip
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, deflate: zlib.createDeflate
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};
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/**
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* Default filter function.
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*/
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exports.filter = function(req, res){
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return /json|text|javascript/.test(res.getHeader('Content-Type'));
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};
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/**
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* Compress:
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*
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* Compress response data with gzip/deflate.
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*
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* Filter:
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*
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* A `filter` callback function may be passed to
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* replace the default logic of:
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*
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* exports.filter = function(req, res){
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* return /json|text|javascript/.test(res.getHeader('Content-Type'));
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* };
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*
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* Options:
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*
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* All remaining options are passed to the gzip/deflate
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* creation functions. Consult node's docs for additional details.
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*
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* - `chunkSize` (default: 16*1024)
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* - `windowBits`
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* - `level`: 0-9 where 0 is no compression, and 9 is slow but best compression
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* - `memLevel`: 1-9 low is slower but uses less memory, high is fast but uses more
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* - `strategy`: compression strategy
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*
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* @param {Object} options
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* @return {Function}
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* @api public
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*/
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module.exports = function compress(options) {
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options = options || {};
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var names = Object.keys(exports.methods)
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, filter = options.filter || exports.filter;
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return function(req, res, next){
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var accept = req.headers['accept-encoding']
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, write = res.write
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, end = res.end
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, stream
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, method;
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// vary
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res.setHeader('Vary', 'Accept-Encoding');
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// proxy
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res.write = function(chunk, encoding){
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if (!this.headerSent) this._implicitHeader();
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return stream
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? stream.write(new Buffer(chunk, encoding))
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: write.call(res, chunk, encoding);
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};
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res.end = function(chunk, encoding){
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if (chunk) this.write(chunk, encoding);
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return stream
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? stream.end()
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: end.call(res);
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};
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res.on('header', function(){
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var encoding = res.getHeader('Content-Encoding') || 'identity';
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// already encoded
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if ('identity' != encoding) return;
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// default request filter
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if (!filter(req, res)) return;
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// SHOULD use identity
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if (!accept) return;
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// head
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if ('HEAD' == req.method) return;
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// default to gzip
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if ('*' == accept.trim()) method = 'gzip';
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// compression method
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if (!method) {
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for (var i = 0, len = names.length; i < len; ++i) {
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if (~accept.indexOf(names[i])) {
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method = names[i];
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break;
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}
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}
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}
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// compression method
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if (!method) return;
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// compression stream
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stream = exports.methods[method](options);
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// header fields
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res.setHeader('Content-Encoding', method);
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res.removeHeader('Content-Length');
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// compression
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stream.on('data', function(chunk){
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write.call(res, chunk);
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});
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stream.on('end', function(){
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end.call(res);
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});
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stream.on('drain', function() {
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res.emit('drain');
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});
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});
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next();
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};
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};
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